Nervous System Structure (OCR)

Module 23: Nervous System Lesson 1: Structure of The Nervous System Encounter the phenomena If you step on several toy blocks, is it going to hurt? Why is this response a good thing? New vocabulary Neuron Action potential Dendrite Threshold...

Module 23: Nervous System Lesson 1: Structure of The Nervous System Encounter the phenomena If you step on several toy blocks, is it going to hurt? Why is this response a good thing? New vocabulary Neuron Action potential Dendrite Threshold Cell body Node Axon Synapse Reflex arc Neurotransmitter  Focus question What are the structures and functions of a neuron ?  P: Neuron 619  P: Video 619 Neurons: P: 619 specialized nerve cells that help you: ➔ gather information about your environment, ➔ interpret the information, ➔ and react to it. Neurons are information messengers: They make an enormous communication network called THE NERVOUS SYSTEM.  P: Neurons consist of three main regions: 619 The dendrites A cell body An axon Dendrites: receive impulses from other neurons and conduct these impulses to the cell body. P: 619 Cell body : neuron structure that contains the nucleus and many cell organelles. P: 619  P: 619 The axon passes the impulses from the cell body to other neurons and muscles. There are three kinds of neurons: P: 620 - Sensory neurons - Interneurons - Motor neurons  Sensory neurons send impulses from receptors in the Sensory neurons signal skin and sense organs to the interneurons (Found in the brain and spinal cord. spinal cord and brain). Interneurons carry the impulse to the motor neurons Motor neurons carry impulses away from the brain and spinal cord to a gland or muscles, resulting in a response. P: 620  Simple Involuntary Reflex The nerve impulse completes a reflex arc : a nerve pathway that consists of a sensory neuron, an interneuron, and a motor neuron. A reflex arc is a basic structure of the nervous system. P: 620  t ur y Skills: e n 21st C l thinking Critica 1. How a reflex might be completed before the brain interprets the event? 2. What would be a possible consequence if you had to wait for the brain to interpret the stimulus and signal an appropriate response?  Simple Involuntary Reflex EXIT TICKET 1 P: 620  P: 620  P: Nerve impulse 620  P: Video 620  A nerve impulse: an electrical charge traveling the length of a neuron. An impulse results from a stimulus, which causes a person to react. P: 620 Explore and Explain: The Nervous System: How Nerves Work Open MCGraw: Explore and Explain: Interactive content (video 1/P2: A neuron at rest)  A Neuron at Rest: Neurons at rest do not conduct impulses. + Potassium ions (K ) are more on the inside of the cell. + Sodium ions (Na ) are more on the outside of the cell. In addition to negatively charged protein molecules in the cytoplasm P: ➔ Inside of neuron at rest is more negatively charged than its outside 620  P: 620 Ions tend to diffuse across the plasma membrane from a higher concentration to lower concentration of ions. Proteins work to counteract the diffusion of the sodium ions and potassium ions: They actively (consumes energy) transport sodium ions out of the cell and potassium ions into the cell. P: 621  P: 621 Outside a neuron Inside a neuron For every two potassium ions pumped into a neuron, three sodium ions are pumped out. ➔ This maintains an unequal distribution of positively charged ions, resulting in a positive charge outside the neuron and a negatively charged cytoplasm inside the neuron. P: 621  P: An Action Potential 621 A nerve impulse is also known as an action potential. The minimum stimulus to cause an action potential to be produced is called a threshold. ALL OR NOTHING When a stimulus reaches the threshold, channels in the plasma membrane open. P: 621  P: 621 Sodium ions rapidly move through these channels into the cytoplasm, causing a temporary reversal in electrical charges. The inside of the cell has a positive charge, which causes other channels to open: Potassium ions leave the cell restoring a positive charge outside the cell.  P: The sodium_potassium pump restores resting potential 621 Explore and Explain: The Nervous System: How Nerves Work Open MCGraw: Explore and Explain: Interactive content (video 2/p2: An action potential)  This rapid positive to negative to positive charge reversal moves along the axon like a wave. P: 621 An Action Potential WORKSHEET ON GC Depolarization: is an all-or-nothing event that is initiated by the opening of sodium ion channels within the plasma membrane. Repolarization: restoration of the difference in charge between the inside and outside of the cell membrane following depolarization.(by the efflux of K ⁺ through K ⁺ channels) Hyperpolarization: is a change in a cell's membrane potential that makes it more negative. (due to efflux of K ⁺ through K ⁺ channels) Speed of an Action Potential P: 622 Many axons have a covering of a lipid called myelin , which forms an insulating layer, called a sheath , around the axon. The myelin sheath has many gaps, called nodes. Speed of an Action Potential P: 622 Sodium and potassium ions cannot diffuse through myelin, but they can reach the plasma membrane at these nodes. ➔ This allows the action potential to jump from node to node and greatly increase the speed of the impulse. ➔ Axon not covered with myelin may conduct an impulse at a speed of only 10 m/s ➔ An axon covered with myelin can conduct impulses at speeds of up to 150 m/s P: 622 ➔ Neurons with myelin carry impulses that are associated with sharp pain. ➔ Neurons that lack myelin carry impulses associated with dull, throbbing pain. P: EXIT TICKET 2 622 Explore and Explain: The Nervous System: How Nerves Work Open MCGraw: Explore and Explain: Interactive content (video 4/p2: Action potential of a muscle)  Visualizing an Action Potential To cause the voluntary contraction of a muscle, a signal from the brain creates an action potential in a motor neuron. This action potential travels along the motor neuron, which leads to the release of a neurotransmitter that signals the fibers of the muscle to contract. P: 623 1. Neurotransmitter called P: 622 acetylcholine (ACh) is released from the axon of a motor neuron. 2. ACh binds to receptors on a skeletal muscle, which results in sodium ions entering the muscle. This produces an action potential, which travels along the muscle fiber and leads to a series events that will cause the muscle to contract. Explore and Explain: The Nervous System: How Nerves Work Open MCGraw: Explore and Explain: Interactive content (video 3/p2: The S ynapse ) The synapse A small gap between the axon of one neuron and the dendrite of another neuron. P: 624  When an action potential reaches the end of the axon, small sacs called vesicles carrying neurotransmitters fuse with the plasma membrane and release the neurotransmitter by exocytosis. P: 624  P: When a motor neuron synapses with a muscle cell, the released 624 neurotransmitter crosses the synapse and causes the muscle to contract. Neurotransmitters: chemicals that diffuse across a synapse and bind to receptors on the dendrite of a neighboring neuron. This causes channels to open on the neighboring cell and creates a new action potential. Chemistry connection P: 624  What happens to the Neurotransmitter after release? Diffuse away from the synapse Enzymes may break it down Taken by the transport proteins in the membrane of the neuron and used again P: 624 Single Neuron can P: 624 communicate with many other neurons. Open MCGraw: Explore and Explain: Interactive content (Page 4: Check) Assign to Students on MCGraw hill  Quiz 1. Which happens first after the threshold is reached for an action potential? A K+ ions enter the neuron. B Negatively charged proteins leave the neuron. C Na+ ions enter the neuron. CORRECT D The myelin coat breaks down, allowing ions to freely cross the plasma membrane.  Quiz 2. Which is true about action potentials? A They move faster on C They move at one neurons that have speed on all neurons. myelin. CORRECT B They move only on D They cannot move neurons that do not between nodes on have myelin. neurons.  Quiz 3. Which is the correct path that a nerve impulse will follow in a reflex arc? A motor neuron → C motor neuron → interneuron → sensory sensory neuron → neuron interneuron B interneuron → motor D sensory neuron → neuron → sensory interneuron → motor neuron neuron CORRECT  Quiz 4. Which is a chemical that diffuses across a synapse and binds to receptors on a neighboring neuron? A dendrite B node C neurotransmitter CORRECT D myelin  Quiz 5. Which is NOT a step that leads to the voluntary contraction of a muscle? A A neurotransmitter C An action potential is released from a travels along the sensory neuron. CORRECT muscle fiber. B Sodium ions enter D A neurotransmitter skeletal muscle. binds to receptors on skeletal muscle. Organization of the Nervous System Lesson 23.2 Bp.625  Focus question: What are the major differences in the divisions of the nervous system?  Video Why are we learning?  P: Organization of the Nervous System 625 The Central Nervous System  Functions P: 625 of the CNS Relay Processes messages information Analyze responses The Central Nervous System Interneurons Sensory Or,................. Or might ……………… might neurons carry...................... relay the info ……………… respond via a informations...................... about the to the brain … reflex arc...................... environment to the spinal cord Thus, Some brain Other Thus, …..… Motor ………………… interneurons neurons the body ………… send messages ………… store the …..… responds neurons ……. of the spinal ……… info P: cord to 625 video The Brain  Cerebrum Cerebellum Brain Hypothalamus Brain stem P: 625  Cerebrum P: 627 The largest part of the brain and is divided into two halves called hemispheres. The two hemispheres are not independent of each other; they are connected by a bundle of nerves.  Cerebrum P: 627 The cerebrum carries out thought processes involved with Learning Memory Language Speech voluntary body movements sensory perception  Cerebrum P: 627 Most of these higher thought processes occur near the surface of the brain. The folds and grooves on the surface of the cerebrum increase its surface area and allow more complicated thought processes.  Cerebellum P: 628 The cerebellum controls balance, posture, and coordination, and is located at the back of the brain. The cerebellum is responsible for the smooth and coordinated movement of skeletal muscles and is also involved with motor skills, such as playing the piano or riding a bike.  Brain Stem P: 628 The brainstem connects the brain to the spinal cord and is made up of two regions called the medulla oblongata and the pons.  Brain Stem P: 628 The medulla oblongata relays signals between the brain and the spinal cord. It also helps control breathing rate, heart rate, and blood pressure. The medulla oblongata contains the interneurons responsible for the swallowing, gagging, vomiting, coughing, and sneezing reflexes.  Brain Stem P: 628 The pons relays signals between the cerebrum and the cerebellum. The pons also helps control the rate of breathing.  Hypothalamus P: 628 Located between the brainstem and the cerebrum, the hypothalamus is essential for maintaining homeostasis. It is about the size of a fingernail and performs more functions than any other brain region of comparable size.  Hypothalamus The hypothalamus regulates body temperature, thirst, Appetite, water balance. It also partially regulates blood pressure, sleep, aggression, fear P: sexual Behavior. 628  Spinal Cord The spinal cord is a nerve column that extends from the brain to the lower back. It is protected by the vertebrae. Spinal nerves extend from the spinal cord to parts of the body and connect them to the central nervous system. Reflexes are processed in the spinal cord. P: 628 Exit ticket 1 Brain Part Part Function Cerebrum Cerebellum Brain Stem Hypothalamus Spinal Cord  i z z iz Qu The Peripheral Nervous System  P: 628 There are 12 cranial nerves that lead to and from the brain and 31 spinal nerves that lead to and from the spinal cord. The Peripheral Nervous System - Include all neurons that are not part of CNS - Sensory and motor neurons - Neurons :Two classifications Parts of: Parts of: Somatic NS Autonomic NS P: 629 Video  P: 629 21st Century skills: Visual Literacy - Why are the boxes for CNS and PNS connected directly? - Why aren’t the boxes containing the somatic nervous system and autonomic nervous system directly connected?  The Somatic Nervous System Nerves in the somatic nervous system relay information from external sensory receptors to the central nervous system. Somatic motor nerves relay information from the central nervous system to skeletal muscles. Usually, this is voluntary. P: 629  The Somatic Nervous System P: 629 However, not all reactions of the central nervous system are voluntary. Some responses are the result of a reflex, which is a fast response to a change in the environment. Reflexes do not require conscious thought and are involuntary. Most signals in reflexes go only to the spinal cord and not to the brain. The Autonomic Nervous System The autonomic nervous system carries impulses from the central nervous system to the heart and other internal organs. The body responds involuntarily, not under conscious control. P: 629  The Autonomic Nervous System The autonomic nervous system is important in two different kinds of situations. When you have a nightmare or find yourself in a scary situation, your body responds with what is known as a flight-or-fight response. When everything is calm, your body rests and digests. P: 629  Sympathetic NS Parasympathetic NS More active in More active in stress times relax Relay impulses to Relay impulses to Is active when the the same organs Restores the the same organs heart and breathing body after rate increase. stress P: Exit ticket 2 630  s kills: t u ry ing n Ce Think s t 21 tical Cri When you stub your toe, why is only the somatic nervous system involved in detecting the stimulus but both the somatic and autonomic nervous systems are involved in the response? Word Wall  Lesson 19.3: Plant Reproduction B.P: 523-531  P: 523 Reproduction Sexual Asexual Reproduction Reproduction Vegetative Reproduction  Asexual Reproduction without the joining of an egg and Reproduction a sperm New plants grow from Vegetative parts of an existing plant Reproduction that are identical to the original plant. P: 523 Advantages of vegetative reproduction: Faster way to grow than from seed or spore Plants produced are uniform in appearance to their parents Some fruits do not produce seeds, so vegetative P: 523 reproduction is the only way to reproduce  P: 523 Gemmae Liverwort Cup tissue  P: 523 Mitosis: is a process of cell division resulting in two identical cells with the same number of chromosomes (2n). Meiosis : is a process of cell division resulting in four daughter cells with a reduced number of chromosomes (n). Alternation of Generations : P: 524  Flower Structure P: 525 Flowers vary in structure and form from one species to another. In each, the flower has one main function: to ensure that the plant reproduces successfully. Flower P: Organs: 525 Some organs provide support or protection, while others can be involved directly in reproduction. In general, flowers have four organs—sepals, petals, stamens, and one or more pistils. Sepals protect the flower bud and can look like P: 525 small leaves or even resemble the flower’s petals. Petals usually are colorful structures that can both P: attract pollinators and provide them with a landing 525 platform. Sepals and petals, if present, are attached to a flower stalk, called a peduncle.  Most flowers P: 525 have several stamens —the male reproductive organs. A stamen is composed of two parts— the filament and the The filament, or stalk, supports the anther. Inside the P: anther are cells that undergo meiosis and then mitotic cell 525 divisions, forming pollen grains. Two sperm eventually form inside each pollen grain. Each sperm cell will eventually fertilize a different structure inside the female reproductive organ. The female reproductive organ of a flower is the pistil. In the center of a flower is one or more pistils. A pistil usually has three parts: The stigma The style The ovary P: 525 The stigma is the tip of the pistil and is where P: pollination occurs. 525 The style is the part that connects the stigma to the ovary P: that contains one or more ovules. A female gametophyte 525 develops in each ovule, and an egg forms inside each female gametophyte  Flower Adaptations P: 526 Structural Differences: Complete A flower with all flower parts Flowers InComplete A flower missing one or more of Flowers its organs.  P: 526 Complete InComplete Flowers Flowers Structural P: Differences: 526 Perfect A flower with both stamens and Flowers pistils Imperfect A flower has either functional Flowers stamens or pistils not both  P: 526 The number of flower organs distinguishes P: 526 eudicots from monocots. When the petal number and other Eudicots organs for a flower is a multiple of four or five Monocots Flower organs in multiples of three. Pollination mechanisms: Different anthophyta species have flowers of distinctive sizes, shapes, colors, and petal arrangements. Many of these adaptations relate to pollination. P: 526 Pollination mechanisms: P: 526 Self Flowers can pollinate themselves or Pollination another flower on the same plant Flowers receive pollen from Cross another plant. Some flowers must Pollination be cross-pollinated, often by animals. Pollination mechanisms: Animal P: 527 pollinated flowers are brightly colored, have strong scents, or produce a sweet liquid called nectar. Pollination mechanisms: P: 527 Wind Flowers that lack showy or pollinated fragrant floral parts flowers - Produce huge amounts of lightweight pollen. - Stamens are hanged below the petals, exposing them to the wind. - Stigma is large: Ensures that a pollen grain might land on it.  Flowering Plants P: 528 - Division _Anthophyta _ largest and most diverse group of plants. - Provide much of food eaten by humans. - Known as _ Angiosperms _ produce flowers and develop seeds (part of the fruit). Seed and fruit development video video P: 528  P: 528 Seed and fruit development P: 528 Endosperm: Tissue that develops from the double fertilization and provides nourishment for the embryo. Rapid cell divisions without cell wall formation _as the endosperm matures, cell walls form _ ➔ Monocots: Endosperm makes most of the seed’s mass. ➔ Eudicots: The cotyledons absorb most of the endosperm tissue and provide nourishment for the embryo. The liquid inside a fresh coconut is liquid endosperm—cells without cell walls. Seed and fruit development P: 528 Seed coat: A protective tissue that forms as the endosperm matures and the outside layers of the ovule harden. Seed and fruit development P: 528 Thin, outer covering that loosens as seeds are cooked. Seed and fruit development P: 528 Fruits: ➔ Form primarily from the ovary wall. ➔ In some cases, fruits consist of the ovary wall and other flower organs.  P: 529 Seed dispersal Fruits protect and help in seed dispersal. Seed dispersal eliminates the competition between offspring and parents for resources. P: 529 Seed dispersal Other ways of Seed Dispersal: wind or water P: 529 Seed germination When the embryo starts to grow P: 530 Seed germination Factors that affect germination: a. Water b. Oxygen c. Temperature P: 530 Steps of germination: Begins when a seed absorbs water, either as a liquid or gas. The seed swells; this can break the seed coat. Water also transports materials to the growing regions of the seed. P: 530  Within the seed, digestive enzymes help start the breakdown of stored food. Used for growth P: of the plant 530 The first part of the embryo to appear outside the seed is a structure called the radicle that starts absorbing water and nutrients from its environment. Will develop into plant roots P: 530 The hypocotyl is the region of the stem nearest the seed and, in many plants, it is the first part of the seedling to appear above the soil. P: 530 In some eudicots, as the hypocotyl grows, it pulls the cotyledons and the P: embryonic leaves out of the soil. 530 Photosynthesis begins as soon as the seedling’s cells that contain chloroplasts are above ground and exposed to light. In monocots, seedling growth is slightly different because the cotyledon usually stays in the ground when the stem emerges from the soil. P: 530 Video Some seeds can survive Seeds Other seeds can harsh environmental germinate soon germinate after conditions, such as after dispersal long periods. drought and cold. Maple Ginkgo Seeds biloba P: 530 Most seeds produced at the end of a growing season enter dormancy , a period of little or no growth. Dormancy is an adaptation that increases the survival rate of seeds exposed to harsh conditions. The length of dormancy varies from species to species. P: Ginkgo biloba Cucurbita 531